The delivery of hydrophilic therapeutics from small diameter wet spun microfibers is often characterized by an initial burst due to drug trapped on the surface during encapsulation (Williamson et al. 2004 Biomaterials 25:5053-5060; Change et al. 1998 Journal of Biomedical Research Part A 84A: 230-237). Rapid drug burst from microfibers is detrimental under the circumstances of a drug having a narrow therapeutic range, thereby resulting in local drug concentrations that quickly become toxic, and little advancement has been made to slow the release of therapeutics from wet spun microfiber-based delivery systems (Schakenraad et al. 1994 Biomaterials 367: 258-260). Previous work addressed double-walled microspheres with drug localized to inner or outer core for controlled release kinetics (Rahman et al. 2003 Journal of Controlled Release 94:163-175; Pekarek et al. 1994 Nature, 367:258-260). There is an urgent need for microencapsulation and phase separation techniques which slow the release of therapeutics from wet spun microfiber-based drug delivery systems.